Terrible internet speed for what you pay

My internet has been off the whole week. They have a great whatapp support team which answers quickly but is unable to do anything besides the usual switch everything off and reset and start up again. First query I made was it has been escalated and to wait 72 hours and then contact them again, which i did. Then they told me to wait another 48 hours and contact them again.

I have a 1 gig upload / down load line which has never been higher than 300 & 400 mbs.