DSL activation problem

Hi. I am extremely frustrated with O2 customer service. I ordered a DSL connection on 13.04.18 which turned out to be the biggest mistake. I was supposed to get the device within 7 working days which did not happen. Then I logged in my early login account and saw that the address was automatically changed. Then I contacted the company and apparently they had sent it to wrong address so I had to cancel my technician appointment for 18.04.18. After that I received the two devices in 5 working days and was given an appointment for 03.05.18 for visit from the technician. After waiting for a whole month, the technician came and did not speak English so I could not understand him properly. He told me that everything is fine, just wait for 15 minutes and your internet will work and left. I waited the whole day but every time I tried to connect I receive a message from Telekom saying that your connection has not been activated however I received the email from O2 that my connection was activated. I then contacted the customer service via online chat and they gave me ticket number 7054071. Then this morning I received the message to call 089666630069. I called thrice, people attend the call but either do not understand English or just disconnect. Then again I tried to contact them via online chat and the made me wait while transferring to a department and then just disconnected the chat. In this whole duration I wasted more than 120 EUR on calls and mobile data just to make my connection work. I am extremely inclined to take legal action because this is not acceptable. I would really appreciate if this problem is solved and I am compensated for my loses. https://#