how to avoid multiple entries on a client list

Hello everyone !

i have a particular problem that i cant think of a way to make it look better.
sooo my problem is that i want to build a "database" of clients with their contact information such as names/addresses/numbers etc along with the products that they "bought" so for example a customer can have more than 1 product which is going to lead in him having multiple serial numbers and different warranties for each one lets say...(fictional and simplified scenario) how can i make the first picture similar to the second one while maintaining the ability to add more products under a customers name without having to insert him multiple times for each product? i'm currently working on a table since i have a lot of functions and when i add a new entry the functions continue on the next row while if i tried to do it like the 2nd picture with filters for example,which also has its issues the functions wont follow. my problem with 2nd picture apart from the functions not following is that if i try to add another entry afterwards by adding a cell everything else will move.

before.png after.png

hopefully i explained it enough for you to understand what i mean xD

TL:DR i want to have multiple entries under a clients name without having to have multiple rows with the clients info for each product, also the S/N warranty must be in different cells so i can flag them with a simple function when the warranty ends for example, and i need the columns to follow up with the functions of the cell above :P

if it needs anything advanced such as vba macros or anything im willing to study and learn how to do it as long as i know where/and what to look for :/

i would also like to thank you in advance for any help/tips that you might provide

thank you for your reply im attaching an excel sample this time with what i ve got so far.... what im trying to achieve i cannot replicate in excel (which is also the reason im asking) so i cant provide an after , apart from the visual concept of the image above.

so my question remains the same, is it possible to keep the format in my attached file while not having to enter multiple entries when a customer has multiple products,S/N , and service dates?

lets say for example that i make some drop down box on a cell that i enter each product? so i have multiple selections in one cell?

or something else than im not familiar with...any ideas tips or suggestions will help me a lot.

PS a little explanation about the spreadsheet,

when years of warranty*instalation date is less than today then warranty is ended"

when next service date is less than today then warranty is void"

otherwise warranty is vailid"

and next service icons appear whether next service should be done on the upcoming month or not..

again thanks a lot for your concern and waiting for your replies

thank you very much for your replies

ill do as you suggested, the next service isnt a problem since there might be occasions where there would be different dates (my bad for not including it) although its not a bad thing to know how to get around it :D.

again thanks a lot!! omw to learn everything i can about pivot now xD

if anything else occurs ill be back otherwise ill mark the topic as solved