I had a roof serviced (mostly front elevation), ie about 8 slates, repointing apex tles and some flashing repaired for about £350 (Midlands). Two men 2 hours work each.
About one months later, a small but significant hole appeared - a slipped/broken slate or similar. To cut a long story short this was a consequence of the earlier work but they didn't want to fix it and I couldn't be bothered to pursue through courts. Anyway after much leaving details and not getting calls back, people not showing up etc I finally got a quote to fix - £410 inc VAT!. In the end I remedied the situation with some foam filler & black paint- cost about £3 minus unused foam filler $2-80, will do fine 'till the roof need servicing next time.
BTW does Britain needs a public categorised internet database, where folks can report a brief description of a job (or quote), location, whether it was done OK and what it cost (but not name/libel who did it!) so that we all know the going rate and when we're being ripped off?. Top of the list would be the category 'new boiler installation'.
Egremont.