Thank you for your enquiry. I am sorry you are not getting along with your John Ryan mattress.
Unfortunately, it would not be possible to replace one half of a zip and link mattress as they are made as a pair, one half of each zip is attached to each mattress.
Without knowing the details of your order, what model and spring tension(s) you have and when you purchased it, I am unable to advise you further. Please call the office on 0161 437 4419 with this information and one of our advisers would be happy to help.