I feel cheated by O2 and its representative in O2 shop

The O2 representatives in O2 shop are not being honest and are providing wrong information They are impatient and try to sell everything that I don't want. I recently had a very bad experience and i unknowingly under pressure made some mistakes too.

My wife’s number is attached to my contract and for some time now she has been getting random calls from stranger so we decided to cancel the contract ending this July, so 3 months prior to that in April during the pandemic I visited the O2 shop to get this number cancelled. I was told it be taken care off and I need not worry. But now I am surprised to see that its been extended for 1 more year. If right information was provided this situation would have not occurred.  Now I know that it has to be done in written form.

Then on 22nd July I get email regarding a discount for iPhone 12, where O2 existing customers pay 30 Euros /month instead of 33 Euros. See link below

http://info.o2.de/r/r.aspx?A4UBsIbwuUfAPnZ2bvzApom0Mw2

I went to the O2-shop to buy this phone as I wanted it to be a gift for my wife on our wedding anniversary which was on the 23rd July. But when the contract came to my email a day later, I was surprised that I am charged 33Euros/month instead of 30Euros. Then to add salt on the wound since I thought my wife number is going to be cancelled end of July. I took a partner sim card reluctantly for 9.99Euros/month. I wanted a pre-paid sim but for forced under pressure for a partner card. I was assured that I wont be paying any additionally fee just 9.99 Euro/month. To my surprise my July bill shows that I have charged 39.99 Euro as a onetime payment and another 39.99 Euro for O2 unlimited data between 24July - 31 July. Why would I need unlimited data when the tariff already had 3GB data. This has been activated without my permission and also deactivated (but charged for a month). I must agree that certain discounts we also given as discussed but I am not sure. The iPhone 12 and the partner SIM are still in their original packets and unopened. I feel very bad and cheated. I have been to the O2 shop twice thereafter, they were very rude and not friendly and asking me to comeback in 2 weeks. That person there told me he would call me in 3 days and they didn't . 

I would rather donate money to the flood victims then getting ripped off in this way. I hope someone here would sympathetic to my situation and will do the needful. I would give one more chance for O2 to get things right otherwise I would be making negative reviews about O2 in every available platform in English and in German and I would name the O2 shop. Lastly I will close all contracts with O2 when they end and jump to other providers. I have learnt my lesson.

A perfect day was spoilt by some incompetent people.