Hathway / Gujarat Telelink [GTPL] — Night internet

My internet does not work ant night time during 9pm to 7am at morning. And i complaining about it to the company and they told me that they solve in 1-3 days but till the date its been 2 week or 15 days but they doesn't solve any problem and my internet stop working. I am complain about it 2 or 3 times but they does not solve my problem.
And if they do not eligible enough to solve my problem then i want my refund.