DSL lamp off (no internet)

My DSL service was activated in May and we enjoyed the internet service for a month. 

However, one day in June, DSL lamp just turned off in my router and no internet since then. 

It was completely fine for a month and turned just off with no reason. 

My friend, who can speak German, called hotline 08005251378 for me and did a reset my router. But, it doesn't solve the problem. Since the line was suddenly disconnected, we have tried to call again a million time after that. However, as you may know, it is too long to wait and easily disconnected with no reason. 

Today, I received a new invoice for a month, even though I have not used any internet service for a month. 

Please do something for me. 

Ticket number: 6653884

Customer number: DE16495797

Rinho