Repair problems & speed up response times for existing Contact Management System

General information for the website: Online Contact Management System
Database management system (DBMS): MySQL
Kind of development: Customization of existing website
Description of requirements/features: We had a custom contact management system built 2 years ago. It worked alright, but over time became a bit slow. Now, it has suddenly just stopped working altogether, and shows erroneous data. We need a DB and programming expert to fix the problems on the site, and speed up the way it works.

The original system spec was as follows:

Allow user creation, delete, edit and user level (admin / standard) assignment.
The entire system will only be accessible to logged in users.

In terms of main functionality, system database consists of the following tables:
- Company
- Contact
- Contact History
- Industry
- Sector
- Country
- Languages

Country - Admins can add / delete / edit country names

Languages - Admins can add / delete / edit language names

Industry - Admins can add / delete / edit industry names

Sectors - Sectors are sub-sets of industry and each industry will have a number of sectors. Sectors shouldn't be duplicated across industries. All users can add sector names, but when users add sectors, they should be checked against duplication. Only admins can delete / edit sector names or place them under a different industry.

Company - Has a number of fields. Each company is linked to 1 country, multiple languages, 1 industry, multiple sectors. All users can add / edit companies. Only admins can delete a company. Each company can have 0 to multiple contacts. A company can have a direct contact history (in the case of 0 contacts) or contact history associated with each contact.

Contact - Each contact has a number of fields. Each contact may be linked to multiple companies, multiple sectors. All users can add / edit contacts. Only admins can delete a contact. Each contact can multiple contact histories associated with each company or as an individual.

Contact History - All users can add a contact history entry. Only admins and the user who added the entry can edit it. Only admins can delete a contact history entry. Each contact history entry is tied to a contact and/or company.

Reporting functionality:
1. Search for companies and contacts based on keywords. Filtering results by industry, sector, country and/or language. Users should be able to quickly export list of results to CSV
2. Admins should be able to run the following reports for each user:
(a) Contacts and companies added each month
(b) Number of contact history entries made each month. Filtering results by specific fields within the contact history

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Extra notes: All work must be fully hosted and installed on our servers.

We may not be able to provide full database access due to privacy and security concerns.