My DSL internet is not working after moving to a new apartment

Hello, 

I moved to a new apartment in February and the technician came on 17th of Feb to provide the connection, he did something in the basement and told me that the connection should be working but after he left the internet was still not working, I contacted the o2 customer service through chat and they said it should work from that evening, it has 5 days since and still the internet doesn 't seem to work !!!. Me and my wife both work from home and we are currently using the hotspot from our mobile to work. This is so frustrating, right now if I try to reach the chat it says the chat is currently unavailable !!!

I tried following the service suite app to setup the router and every thing but still the internet does not work. Only the DSL light is green, the internet light on the router is switched off! please help.