Had a couple of texts lately like to cancel no reason do you mostly ignore it and move on or text back ask for reason
Depends how long you've been running.
Newly started or just converted to WFP, I'd give them a quick call. Be clear you're not trying to change their minds, just trying to find out if it was a quality or service problem.
Been going for a while and confident of quality, I'd just say "Thanks for your business in the past: if you need us in future, please do call."
Or I'd go and wipe dog mess under their door handle.*
Vin
* Included to keep the neanderthals off my back for being a pushover...