Deluxe Laser & Spa Cloud Nine

I had a voucher for a spa treatment that was valid for 3 years. I went for the treatment and when I came out they then said the voucher was not valid, even though, on the voucher it shows the expiry date and I went before this date. I had to pay them and have been fighting for months to try get my money back, with no success. This is outright *****, theft and unjustified enrichment under the law. I am taking this to my legal team out of principle now so that nobody else will be ****med.