normally in these circumstances (only had a few) i will help them put right the cowboys wrongs. but in one or two cases if the customer is being a "You know what" ill be just as unpleasant back.
example:
had one very regular customer who got her boiler done by another company, in the winter its condensate pipe froze. i went and sorted it out for her and charged her accordingly. she got us in to do a garage conversion into a laundry room and also install a new radiator. plus shes passed our name onto a few other people.
the other customer of ours:
a landlord/builder (medium sized company) weve done a few jobs for him in the past and every single one has been a nightmare. i hated every minute of working for him. he wanted things doing there and then (did a boiler swap the day after boxing day as tenants were moving in the day after as no one else would do it). we did the job and got everything up and running, stayed till 10pm to get it running in time, he met us at the house the next morning to sign paperwork, he didnt even say thanks and didnt even smile. since then weve done a couple of other jobs for him hes always been miserable and ungreatful at the lengths weve gone to help him out, most recent one was a couple of weeks ago. he wanted the new build house finishing off (supposed to be an 8week project..... 12 months later it was still not ready for us to finish) he rang us out the blue and wanted it finishing by tomorrow, i said sorry but im on another job which is at least 2 weeks long. he replied "i dont care about your other jobs get it done by tomorrow" since then i havent answered the phone to him but i have completed the plumbing side of the job, havent told him that yet tho. im letting him sweat a little since hes to lazy and arrogant to drive down there and have a look. hes by far the worst i have ever worked for and once i get paid the last installment for this newbuild i will NEVER work for him again. even the other bloke i work with refuses to have anything to do with him. in all my years ive never met anyone who can rub me and the rest of the world up the wrong way like he can. a PRIZE (you know what) comes to mind