Den Networks — den broadband service - continuous disconnection and poor speed of internet.

I have installed den internet for my family 1 year back. Now because of covid-19, i came from hyderabad and doing work from home in delhi. From last 15 days, i'm noticing that my internet lost after every 15-20 minutes and my vpn get disconnected. I have to again login back to vpn. I raised the complaints and they say that they are fixing the issue back-end. Sometimes the technician visited my place and changed the ip address but still facing the issue. I paid for 6 months package with 50 mbps speed in last week of february 2020. Just because of work from home, i noticed this continuous disconnection of internet on my laptop, otherwise it was not noticeable on phone by my family members. It is hampering my office work. I don't want to use this internet service and want refund of my remaining month's amount.
Customer user id - pan_77545