Modify Yith Automatic Role Changer Plugin

I need some changes to an existing Wordpress Plugin called Yith Automatic Role Changer. The only extra functionality I want within your Yith ACR is: SWITCH default Role to (specified role) When they buy: Specified Product For X Days (let's me choose in days. Examole: When a user buys product Gold Membership they switch from the Default role (Customer) to (Gold role) for 30 days. After the 30 days is up (Gold role) is removed and they gain back (default) Customer Role. I want this done ASAP, it's a quick modify. I am on a Strict Budget to £12.00 if you cannot accept this please do not bid.