Paul,
I would go in at £130, plus try to push half price protection treatment.
You can be sure that CD will quote for protection and you can beat them on that.
If the carpet takes a beating, protection is a must. Try to look at it as an ongoing account.
Protection makes it better for them ( longterm ) and easier for you to clean.
Quote a reasonable price, speak to the person making the decision to promote your
professionalism and you are in with a very good chance. If you don't get it at that price, it is probably not worth it anyway. Be prepared to lose some!!
Jim