Building Customer Database for to maintain quarterly maintenance schedule

I own company which is specialized into security systems like indoor and outdoor cameras. After installation of security system, one year contract will be signed with the customer and we will be responsible to do 4 times maintenance visits during the year to assure functionality of the system. However we don’t have any customer database that’s why I started to collect all customers information in excel sheet where all critical information for each customer should be available like : • Customer information details ( reference number , shop name, address , phone number etc..) , • System specification ( no. of cameras, model number, brand name etc..) • Contract and maintenance dates which include date of contract signatures and dates of 4 times visits across the year. each visit will be 3 or 4 months PLEASE UNDERSTAND THE FOLLOWING : the sheet already created . i just need to enhance it with some excel features like conditional formatting , formulas and fitering option. this is what i need only . no database no php no web application nothing it is just an enhancement of exiting excell sheet. this is very simple project. Check the attached excel sheet which shows my customer database sheet. This is where we can start and build.