Viomi V3 Robot Vacuum Battery Performance Keeps Dropping

I purchased my Viomi V3 robot vacuum from Teknosa about three years ago, and for the past month it has not been working properly. Even while sitting on the charging dock, the vacuum repeatedly announces that it is charging. Although it appears to reach a full charge, its cleaning performance has noticeably declined, and it no longer cleans as efficiently as it did when it was new.

So far, I have not contacted either Teknosa or an authorized Viomi service center, but I believe the problem is related to the battery. I request that my robot vacuum be inspected, that any necessary diagnostic tests be performed, and that the issue be resolved by installing a genuine replacement battery if required.

I expect a prompt and solution-oriented response from Teknosa so that my issue can be resolved and my robot vacuum can be restored to the level of performance it had when it was new.