Having big problems with virgin phone line?

Unfortunately you are under contract to virgin so you will not be able to cancel unless you have had the line for 12 or 18 months depending on your contract however I would suggest calling them and telling how long that the service has been bad and demanding compensation for the bad line. I had low broadband speed because of a faulty cable for almost a year and got a fairly large compensation when it was fixed. You have to be demanding with them to get it but you're entitled to it if they can not provide the service they promise. As for switching to another supplier that isn't possible on a virgin line. You can only switch suppliers on a BT line. REGRETABLY its patience and keep at them. Call every day