From
https://www.pokerstars.uk/tos/ (but the terms may be different where you are) :
16. How to get help with or make a complaint about the Services
16.1
If you need to contact us, either with a general query or to make a complaint, please use contact support. You can also search questions and contact us via the Help Center. Our customer support representatives will ensure your query is answered or referred to the appropriate specialist team.
16.2
If you have a complaint, please provide us with as much detail as possible. We will acknowledge your complaint within 24 hours from when we receive it, and we will provide you with a final letter as soon as possible and in any event within 8 weeks of the date we received your complaint. In the letter we will let you know our final decision, confirm that we have reached the end of our complaints process, and explain how to escalate your claim should you wish to do so. If you do not provide us with adequate information to help us process your complaint then we may not be able to keep to this timescale for handling it, and we may ‘stop the clock’ and wait until you provide us with adequate information.
16.3
If you feel your complaint hasn’t been satisfactorily resolved within 8 weeks of the date we received it (taking into account any periods when the clock was stopped), you may choose to contact our third-party dispute resolution provider, IBAS. For further details visit IBAS’s website here. There is no charge for using IBAS.