my idea is to be vigilant immediately you receive a bill. Five months into a 2 year basic contract of £20.99 /mth, I was charged £22.95 despite contract letters which stated "guarantee your price stays the same ..." and "no sneaky mid-contract price rises" and " peace of mind for the length of your contract" . These are their words, not mine. If you find your contract violated, as mine has been, I suggest you follow Talk Talk's complaint procedure on their site. Not easy but good luck!