My phone went missing at Huawei when taken for repairs

I took in my phone for repairs at Huawei in Melrose arch last year. When I went in to collect it, I was told that someone already collected it, but there was no paper trail of who they gave it to and why they gave it to a wrong person. Untill today I still don't have my phone, I was told they will notify the head office and investigate the matter but no one came back to me, I emailed them several times with no response, I have been to their shop several times, the manager always says he will get back to me but he never did. I need my phone back please Huawei