Curtains shrank at dry cleaners

[AnnieMay55]

Just got my curtains back and they have shrunk 17 cm / 6 3/4 in. I was warned they could shrink up to 1 1/2 in which I thought I could just about cope with as they said they might not shrink at all. They are full length on patio doors and cost over £500 made to measure 10 years ago.
They also match another pair which I didn't have cleaned, in the same room. The cleaners are now supposed to be coming back to collect them and put them on their stretching machine. Has anyone ever heard of this and whether it is likely to work? They are now uneven with the lining hanging lower.

I wonder what rights I have if they don't get them back to a usable condition especially as to replace means replacing the others in the room. The material is no longer available. The two pairs cost nearly £900. Can I expect a contribution to their replacement?

If all else fails, I think the hems could be let down, usually at least 6” longer than the curtain, and a strip of matching fabric added to create a false hem. More lining material could be added to the linings, if you have them. None of these amendments would be visible on the right sides of the curtains and certainly much cheaper than total replacements.
Were they dry cleaned or washed. I didn’t think fabric shrunk if dry cleaned but I may be wrong.
No idea about your ‘rights’ but hope you get it sorted.

Where did you buy the fabric OP? What is it made of?

It should have come with dry cleaning instructions. If they shrunk despite appropriate cleaning, I'd want to discuss that with the original supplier.

@gingergiraffe the hems aren't as deep as 6 inches but possibly a false hem could help. Thanks for the suggestion. Not sure if the crease from the current hem would be easy to remove or if it would show wear. They were dry cleaned but I'm not sure how they do it. I think they get dampened. It does say online that things can shrink when dry cleaned. @Meadowfinch They were bought from and made by Laura Ashley who are no longer in business. Some of there curtains are available elsewhere but not this fabric. They are a cotton and linen mix material.