RE: Dell Inspiron 7567 touchpad problem
I also think your issue is not hardware failure. Specifically, what was your request of them? Did they state why they refused? The only hardware issue I can find related to the touchpad was being loose and rattling. Your issue sounds more like software, driver, or operating system. Read through this and see if it helps.
Social Media Support
Run the PC pre-Windows diagnostics
Where do I find my Dell PC Service Tag or Express service code?
Out of Warranty Support