PHP script customization

Hi I've recently bought an SMS PHP script but I need it to be customized adding some features as follows: -After registration user must have Bulk SMS/Email active (now only the admin can do it) and redirected or suggested to buy an SMS plan in the already existing page. -the princing plan page its ok but user must also buy a number from the gateways in order to start sending bulk sms (i think this is possible through sub-numbers, i.e. Nexmo, Twilio,Clickatell..), in the same page, before the pricing plan will be ok. -The User new sub-number (sub of admin's number) will be the default sending ID, but will be great to be editable as it's now. -add export&import for contacts on users account, now there is only export. Admin instead has both. -User must be able to receive messages too. So add, under Bulk Sms, a label for "Text-inbox" messages for incoming SMS (many of the gateways listed have OPT-IN api to integrate on) -User must be able to manage SMS autoresponders by adding keywords. example: a customer writes to his number a keyword will receive an automated message. in a new page "keyword mobile", under Bulk SMS. -add pricing plan (like for sms) even to bulk email, editable by the admin as sms. If you have concerns questions or suggestions don't hesitate to ask. Bye