A dreadful firm. Advisors at their call centres are of no use, not trained properly, very poor service. We have left o2 as the price was costing too much for the service. It took three months contacting them by ringing and emailing. Their staff said everything was sort and would send a code to give to our next firm, and o2 never sent the code. After finally leaving them, they sent me an email to say we were £0.35 in credit. We paid everything we owed them. Now after nearly three months of not being with them, o2 is sending a bill each month with threats. I give up. Do not go with them, they over charge, we were paying over £27. each month and hardly used the data etc. They never thought to offer a better deal until we said we were going else where for £6.95 each month with a better deal.