Mts — Speed is the issue

Address:

New Delhi, Delhi

I m living in east delhi, I have been using mts wifi data card since 2 years and now from last 3 4 months its speed had gone down to 2g speed infact worst then that . 3 4 times i have called customer care and they say we will solve this issue soon ? What is the problem ? Do i have to switch to some other network or my problem will be solved ?