Hi @StoibMax, welcome! I am a little bit confused as to what the problem is. Taking over a contract is an administrative thing. The contract gets registered to your name and billed to you instead of to the previous person. This generally happens during things like a divorce, or someone moving into a house with an existing contract. I'm assuming that last thing is also the case with you? If so, nothing should have changed. All the equipment (Experia Box, any tv set top boxes) are part of the contract so should still be there and active. 

So, what is it that you need to activate? Also, please fill in your forum profile so that I can check things here if need be.