The "probably" and "just make sure" parts of your response are exactly why I'm getting someone in who will get rid of those and provide a guarantee. Anyone else used a locksmith and can compare costs?
Have you been quoted a particular price? I wouldn't be surprised if it is in the region of £125-150. £50-60 call out, £50-60 for time on site, rest parts.
The "probably" and "just make sure" parts of your response are exactly why I'm getting someone in who will get rid of those and provide a guarantee. Anyone else used a locksmith and can compare costs?