Complaint regarding o2 services - On the verge on going legal

I bought this multi boost plan in Jan 2022. Since I bought this plan it doesn't work and I complain to your customer center every day.
After 1 week of endless calls with no solution I asked to cancel the contract as I was in the 14 day cooling off period.

They told me it's been processed and I'll get a confirmation in a while. I did not. I called again and they said there is no such thing in the system and they will do it again. This has been going non-stop for 3-4 days. I called 6-7 times and each time I got new information and customer center said it will be done. I have raised this request multiple times, send out emails, filled out forms but every time there is something new. The customer center is just pulling blames on one another and then doing the exact same thing. This is the worst service I have had in Germany so far. All the calls should be in your system as they were recorded by you.

Today, if it's more than 14 days, your customer center staff tell me that there is still no cancellation request in the system and I need to send you a letter. This is very wrong and total fraud.

Why should I pay for a service which isn’t working and that too for 2 years.

Please, as a final request please cancel this contract. I am totally fed up with this bad service and spending every day 2-3 hours with customer center for the same issue. I don’t want to continue with this at all.

Regards

Gaurav