O2 just make it hard to pay them the remaining settlement fee. Think it's just so they can squeeze every penny from there customer base having to wait 30days then an extra 15days just to cut you off. I paid £200 upfront to get a contract with O2 but unfortunately the connection was terrible cutting out on business calls & family emergencies. To top that off it seemed impossible to change the dates for when the money comes out because majority of the staff members are pretty useless. Also my bill was supposed to be £50 a month but I started getting charged £75 to £90 a month for a sim that didn't work. It actually worked out cheaper to cut off all tariffs paying only £20 a month then having a second SIM with smarty for £20 a month unlimited everything. So due to the prices constantly increasing I tried to terminate the contract in the first 3months of having it & trust me the staff members made it impossible.  I wouldn't recommend O2 if you want anything reliable.