Very slow Internet

Hello,

I am using o2 for few years and have the 50 Mbps connection option for my home. For the last few months, the internet speed has dropped very low and it is only giving a download speed of 1 mbps. With this speed it is impossible to work and it does not justify the price. I have already tried all the neccesary actions like restarting and resetting. and the speed remains bad. Is there any way for o2 to improve speed? I am living in Kinderhaus-Münster (48159) . Also the high ping results in lag. Kindly respond.