You need to differentiate between T5 as a general terminal building that HAL are responsible for and tenanted areas such as the BA lounges.

T5 itself is in pretty good condition and has been refurbished in many areas since opening; retail units are almost constantly changing and a luxury retail zone was created just a few years ago. The Flight Connections area was reconfigured significantly in the last couple of years too.

HAL are not responsible for almost everything that is visible inside the BA lounges; that is firmly BA's domain.

It's interesting to compare the general terminal toilets and those within the lounges; the latter are in a significantly worse state despite lower usage.