Could you guide me on the procedure to file a complaint against the registrar?
Essentially, the registrar has restricted access to my account due to non-payment for the renewal of one of my domain names, thereby preventing me from accessing my remaining domains.
I do have one .info domain left (technically two), but since it has no significant value, it is merely a curious matter whether to use it for a project or let it go to waste.

ICANN is seizing domain names abruptly, which can be quite challenging. It requires a level of proficiency in English and validation of one's identity through remote means from overseas.
Unfortunately, some individuals who were initially unable to challenge the registrar 1and1 fell prey to their deceptive practices.

It's important to note that domain name seizures can have significant repercussions on businesses and individuals alike. As such, it's crucial to stay vigilant and seek legal assistance if necessary to avoid any potential conflicts or loss of assets. Additionally, maintaining regular communication with the registrar and keeping up-to-date with domain registration requirements can help prevent complications downstream.

In most cases involving domain ownership disputes, the alleged fraudster only appears as such from the perspective of the accuser. The registrar views this individual as just another client until there is evidence to prove otherwise, such as a court ruling that deems the domains in question are a trademark infringement.
It's uncommon for the hosting provider to be persuaded into altering the site owner's actions, although it may be possible through a well-crafted communication strategy.

It should be noted that certain registrars may take aggressive actions against customers without just cause, which can be a sign of fraudulent behavior. Such entities aim to acquire as many domains as possible and park them for profit. For individuals who encounter issues with their registrar or hosting provider, filing a complaint with ICANN's compliance department may be helpful.

In general, when dealing with domain disputes, it's essential to maintain clear records of any communication and legal documentation related to ownership rights. This information can prove instrumental in resolving any conflicts that may arise.
See below:
https://www.icann.org/compliance/complaint [nofollow]

Review the terms and conditions of the registrar to understand the policies regarding domain name renewals and account access. Take note of any clauses related to non-payment and account suspension.

Next, gather all relevant documentation, including invoices, payment records, and correspondence with the registrar. This will help support your complaint and provide evidence of any wrongful actions on the part of the registrar.

Contact the registrar's customer support or complaints department and request to speak with a supervisor or manager. Clearly and calmly explain the situation, providing all the necessary details and documentation. Express your dissatisfaction with the restriction of access to your account and your remaining domains due to the non-payment for the renewal of one domain.

If the registrar's response is unsatisfactory or if the issue remains unresolved, consider escalating the complaint to relevant regulatory authorities or industry organizations. This could include filing a formal complaint with ICANN (Internet Corporation for Assigned Names and Numbers) or seeking assistance from consumer protection agencies.

It's important to maintain professionalism and persistence throughout the process, keeping records of all communications and actions taken. While it may be frustrating to navigate the complaint process, advocating for fair treatment and accountability from the registrar is crucial in protecting your rights as a domain owner and customer.

As for your .info domain, consider the potential value and relevance it holds for any future projects or initiatives. It's always worth exploring the possibilities before deciding to let the domain go to waste. Conduct a thorough assessment of its potential use and weigh the benefits of holding onto it or possibly releasing it for someone else to utilize.