AIBU in expecting better customer service?

I would e mail the head office and try to get a refund for this. Everything sold has to be fit for purpose and this does not seem to be the case here.
Try this and see if you have any results. It seems that it would be a small price for them to pay to keep good customer relations.
Do not give up,

I totally agree it is not fit for purpose .I have phoned Customer Service , I have asked them on Facebook and have emailed their CEO in Glasgow.They do not want to know.They all tell me to take it back the shop in Madeira where I bought it.They will only help if I had bought it from a Trespass store , not even a store in the UK that sells Trespass products, it has to be one of their own stores.I live a 5 minute walk from a Tresspass store so swapping the ' nut' would not be a great inconvenience for me, it would cost them next to nothing , and they would be getting compliments from me not as many angry posts on the many groups and Forums I am a member of.Hubby reckons he might be able to do a ' Heath Robinson' on it and make a part that will have to be screwed in place ( to grip the thread) each time I want to use it, but this means carrying a screwdriver and pliers around to extend it when I wish to use it.No use to me fully extended all the time as it won't fit in my rucksack or suitcase, and not convenient in Madeira getting on and off buses etc....Have emailed the shop in Madeira, in English( I hope they can translate to Portuguese) to ask if they will sort it out next year when I go on my Winter Holiday, it will be over a year since I bought it and I doubt it has any sort of guarantee as it is Trespass product.I hope they make note that I have discovered this fault when it is less than 5 months old and used only twice.The reason I am so annoyed is because it is ' like new' .Not even got any dirt or mud on it.I could have bought one in Aldi for a quarter of the price.....aaarghhh.

Go to a site called ceoemail.com. This will give you the email address of the managing director. Send an email describing the problem as you have in your OP.
I did this with John Lewis, and I had an email within the day from the manager of the problem department to sort it out. If the customer service department refuse/can't sort things out, then always go to the top!

Just seen your latest post so sorry that didn't help you. Did you buy it by credit/debit card? You may be able to get a refund if you did.

That's exactly what I did.Got the CEO's email address of that site.Glad I didn't pay for a stamp, throwing good money after bad.

Thank you very much for that, Badenkate! I bought train tickets online last month from Northern Rail and when we arrived at the station we found that the train's departure time had been altered weeks earlier and we, and others in the same situation, had missed it. Consequently we were over 3 hours late getting home. The company has completely ignored the two complaints sent via their website , so let's see if we can get an acknowledgment from Mr Alex Hynes!

I would not start trying to rectify this yourself by adding screws etc as this may invalidate any rights. I agree that it is best to get the name of the ceo or highest level and let them know what has been going on. I did this with a well known company and got immediate recompense. I think that they try to find easy way out in first instance and if you accept initial response that will be it.
It almost becomes a matter of principle in the end.

Take it to your local store and speak to the manager. It's worth a try.