Magento Expert Required

Hi, Kindly do not BID until you do not read all specs. Required Magento Expert who can resolve following issues. Overview 1- System have extension "Customer Price", which enables admin to change product prices for customers. ([login to view URL]) 2- We have edit order module which enables admin to change payment method and edit shipping price and product prices. 3- We have custom method of shipping "Get a Quote" when customers selects this method system will not charge shipping and customer can pay order amount and checkout. After that admin can finalize shipping amount with customer and edit shipping price which will be added to customer order or invoice. Issues to resolve 1- When customer completed the order (paid by paypal/credit card or Bank transfer) with given special prices on products to the customer. when we edit order to add shipping price to order total becomes to original price and merchant declines payment processing due to change in order. ([login to view URL]) 2- Invoice totals and added shipping amount not working. ([login to view URL]) 3- On front view we need payment option for customer to pay any balance amount which is edited in order by admin. ([login to view URL]) 4- In front view customer is notified and in orders view it should show proper paid unpaid balance amount in his order-invoice-shipping. ([login to view URL]) 5- When any changed made to order in payment customer will receive an email intimation with direct payment link to pay balance amount.([login to view URL]) Requirements: 1- We like to offer (xx)days of credit to customers which will be enabled or disabled by admin in customer view and admin can define days of credit to customer or to order. in this case we can credit shipping amount and may requires shipping amount to be paid. 2- Customer can pay his invoice anytime during the period of credit and will show credit days in customer dashboard which will show as counter. 3- If the credit days limit exceeded system will generate daily email to customer that he has overdue invoice to pay with payment link 4- With credit time customer will receive email after every 7 days that he had due invoice in (xx)days 5- In admin dashboard it will show due and over due customer invoices. If there is anything to ask please feel free to discuss.