On what terms did you request a quote?
If you’re looking for a design and a fitter, I would say to the people you’ve asked for quotes that you will select your preferred fitter on the basis of:
- their price
- their workmanship/reliability
- their availability
- their proposals in terms of units and design.
That way they have to submit all of those (but make it clear that there needs to be scope for design development)
In an ideal world you’ll have a design and a preferred unit supplier before you go out to get quotes, and then the fitters can compete against each other via their trade discounts. However, if you’re not able to do that, I’d suggest the path above.