DE-Install Billsafe Plugin Magento

I need help to de-install a plugin from Billsafe // Paypal. Actually this plugin is a nightmare - what I did not expect from a professional plugin from a company like Bissafe - Paypal. Status Quo: - I can't deactivate the plugin // module without crashing admin interface (Orders / Invoices) + checkout ([login to view URL]) - I use another payment module from novalnet but the billsafe module rewrites magento core functions so I can't use the credit memo function for example for other payment methods, e.g. app/code/community/AwHh/Billsafe/Block/Adminhtml/Sales/Order/Invoice *Filename : *[login to view URL] $this->_removeButton("capture") - After changing the function within the credit memo the button "Update QTY" is still missing. I expect it's also done by the billsafe module but I can't find the function for it. - Installed modules by billsafe: AwHh_Billsafe, AwHh_PaymentFee, Netresearch_Billsafe So now I would like to remote the whole plugin from the shop. But I really don't know how. Please contact me for further information. The problem is within the live environment. You need to backup the software... The project is complete when billsafe is de-installed and all functionalities are working - Admin + Checkout.