Poor customer service

I returned an iron at boardmans canal walk in January as it had a problem the lady who assisted me took my receipt and said I won't be able to keep as it needs to go for repairs, I was surprised about keeping the receipt however I gave her. 3months later I went to enquire about my iron as I have never recieved any feedback while it went for repairs found the same lady who helped me however this time she acted all surprised about keeping the slip but she recalled me. She didn't know what happened to my iron so she asked if I can leave contact details she will follow up and let me know. It's now 6months since I took my iron to them and no one knows where it is,to my surprise when I went back on the 10th I was asked lots of questions and was told I need to remember when did I buy the iron and what type(made and model) of an iron it is by the very same lady.I know the made but not the model, I left my contacts with other lady( I think she's the supervisor) as she promised to contact me. She did contact me few days later to tell me her manager says there's nothing they can do as I do not have any documents for my iron,but how is that my problem because one of their stuff didn't do their work properly. She said I don't need the slip even thou I asked her numerous times if she's sure about her decir,now does that mean I have just lost and I should give up. That's very unfair that poor customer service has to affect me.