No internet connection

Since Sunday afternoon I have had a very unstable internet connection, disconnecting every 20seconds for about 5minutes to even 20minutes at a time. Once the disconnections stopped I see that my connection is limited, I cant go on to any websites NOTHING, only thing that works is when I connect my phone to wifi then all I can do is whatsapp. This has been 4days now and nothing is being done about this. They say they have some problems but my friend with the same connection has no issues. This is very bad customer support.