> Because we have had such poor speeds I have access to 4 phone lines. It has made switching between providers simpler, as I never lost all my connections at once.
Aside: you might be interested in Andrews & Arnold L2TP service, where you get static IPv4 and IPv6 addresses from aaisp, but access them via a different ISP's connection. £10 per month.
I don't know however whether it supports any sort of multipath to allow you to aggregate your lines together - but it would be worth asking.