Petition Force mobile providers to sell pay as you go mobile phones that are not locked

I would like all mobile companies to sell pay as you go mobile phones that are not locked to their network. If you choose another sim only deal it takes weeks to get the unlocking code from your current supplier and doesn't always work you are then faced with weeks more of phone calls, letters etc to get the unlock code which actually unlocks your phone. They normally charge around £20 for this service aswell. I feel that as you have bought the handset outright the mobile providers should not be allowed to lock it to their network as this is preventing healthy competition and also is getting people to purchase new mobiles which means their old ones are being put into the bin