Need to book an engineer to replace our ancient TiVo boxes

So we have two original TiVo boxes both capable of recording but one of them seems to be having a hard disk failure as it keeps updating and when it’s done it’s like a new box completely blank of everything. So I think we need to book an engineer visit. Specifically if possible we were hoping to replace both boxes with v6 ones so we would both still have recording space. Since this is an unusual request I thought I’d post on here to try to sort it as I don’t know which staff are aware of what boxes are available.