I have 15R 5520 INSPIRON DELL laptop and the touchpad hardware problem occur in my laptop,
what i do, if i will send laptop to company / service centre.
If the system is under warranty, start by calling your local Dell support number.
If the system is out of warranty, see here
for flat-rate out of warranty service ($159 in the US for anything other than a screen or mainboard replacement).
You can also contact the computer repair shop of your choice.