Hymer TV sound

I have a Hymer caravan that came with a "Caratec" surround sound amplifier unit fitted. When the van went for service last year I was told that this unit was out of warranty over lockdown and the cost of  a new one is £IOOO+ as it's German. 

I am looking for unit to replace this "Caratec" one. The TV will play through it's  speakers but with an annoying echo.

Does any one out there have any Ideas PLEASE?

Howard Keighley

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