What are my chances of a refund?

Less than 12 months ago I purchased a cordless lawnmower from what is probably the UK's largest DIY store. I have just contacted them with regards to purchasing a replacement blade and they inform they don't stock spares for my particular model. I have also been onto the manufacturers website who give a web address and guess what, it's the DIY store i've already contacted. I sent the manufacturer a email and they tell me i may get the replacement from another UK DIY store. One even told me i may get the blade from China (where the machine is made) My query is do you think I have a case for returning the machine under the 12 month guarantee for a refund. It is after all not serviceable merchandise if i cant get parts