The IVR system should answer every call automatically. If it doesn't, you are probably calling the wrong number. If you don't have a flat rate on your mobile phone, you can also use the free number 08005251378. 

Hello @sumitnath and welcome to our o2 community :-)

I am sorry to hear there are issues with your DSL connection, especially in times like these where a working internet connection is crucial.

Were you alread able to contact our technical DSL departement? :-)

Regards,

Lars