I would'nt have told the customer that you though it was down to fitting unless you were 101% sure that it was, you are precived as a expret by the customer and having seen what can happen next i understand why shops/carpet fitters have such a low opion of carpet cleaners, and if you can work with them you always get more work.
the flip side is
Customer goes to place they bought the carpet and says Calmore came to clean my capet and he says " your fittings not very good" imediatly you get the shop and fitters back up ( you'll be as popular as flu with them) , promting coments such as " is he a carpet fitter" and you'l have put a idea in customer head that will take some shifting.
If i was unsure what the cause of the wrinkling was, or even if i had a good idea I would say
" i notice/yes you have wrinkles in your carpet, you may want to speak to the shop you bought it from and ask them what they think, if they would like to talk to me because i've seen it, hears my number"
If the shop calls on the phone tell them "I'm pretty sure it's delamination/floor boards/ wear area/ crop circles ect but you it's your customer and i did want to upset them, so though you might want to check for yourselves and see if there anything you can do, give me a call if you need my help"
In a perfect world fitter or estimator goes out looks at it and say, yes the cleaner was right, we'lll get that sorted out for you, then you still get the job once that is done ( customer is not going anywhere else again your the guru of carpet now)
And hopefully the shop are bright enough to realise they now has someone to clean carpet that they can trust to do a good job.
Mind you does'nt always work that way
True story.
one month ago fitter on a recomend from another fitter who i helped out last year, who in turn got us from a recomend from a shop he was working for, (long winded i know)
Rang me in desperation,apprentice had got blue gripper glue on a cream twist right in the middle, he been told by his fitter mate "ring paul, but don't touch it yourself, you'll make a mess and he won't be able to do anything" which make my job easier.
I was'nt nearby but told him to murder his apprentice first but not near the carpet hide the body and i'd be there in a hour, then I skiped lunch and dove 20ish miles, and turned up spotter and pog in hand and hey presto! day and carpet saved, now he's telling customer when he's fitting lounges ( hey you can get your hallway freshend up, to match ect,) they are the easiet jobs to book and do. Rember it's as it's one pro recomending another. Best recomend you can get, I had three biggys in first couple of weeks.
p.s i was amazed that it came out as well!