Restonic mattress not good Quality

I bought a Restonic mattress from Lewis last year and the first mattress was not even 6 months old and started tearing on the side by the stitches. Restonic replaced the mattress in May 2023 after my complaint but now the replacement mattress is also tearing on the same place by due stitches on the sides I logged the complaint again this month Oct 2023 with Restonic and Faith told me they cannot assist me my warranty has expired after 6 months I don't understand how the replacement mattress can have 6 months while it was replaced in May 2023