Need to make a Complaint accepting system

I wish to develop a complaint accepting system which accepts the customer's complaint this will require the following tasks

1. Creation of UI ( we already have a UI design)
2. Creation of db tables in MySQL
3. Acceptance of documents related to complaints and storing them in tables
4. Pull the customer information from API and existing database on basis of search keys such as phone, email, firstname, last name, pincode, etc
5. once the customer is searched then select the account on which customer needs to file complaint, please note one customer can have multiple accounts
6. Search the account of the customer and pull the transaction and its details from a database or an API
7. Select the disputed transactions and fill a questionnaire for each complained transaction
8. ask for documents required for the complained transaction and associate the documents with the complaint number
9. Generate a complaint number
10. Send email to customer
11. Maintain audit trail of all the system events
12. User access management