The Wishing Beast & The Vanity Box, by Paul Magrs, is quite an odd little play, almost fairy-tale like in some aspects: the soul-eating vacuum cleaner in particular strikes me as updated Grimm. It gives, at the least, Colin Baker and Bonnie Langford another chance to show that they were let down by scripts in the 1980s, and imagining Geraldine Newman as Scott Summers provides much amusement. Newman and Jean Marsh (of Sara Kingdom fame) do have exactly the right chemistry for the script. But it's a shame it's a little inconsequential: beyond the identity of the box (personally, I think it's the same as Crusade's Apocalypse Box) there's no twist: the two evidently suspiciously nice characters you are introduced to at the start do justify your prejudices. Big Finish does Scooby Doo?
Frozen Time, by the omnipresent Nick Briggs (the Voice of the Daleks) is a much more straightforward base-under-siege romp, yet somehow ends up more satisfying. Like the previous McCoy adventure, Valhalla, this sees him alone, and somewhat more disoriented and world-weary than usual. Doctor Who stories, especially those with solo Doctors, and especially on audio, with the need for scenery-setting as well as exposition, generally see the Doctor acquire a character from the setting as a sort of temporary companion. Genevieve (Maryam d'Abo - yes - that one) fulfills this well, and it's even hinted that there were many subsequent offscreen 7/Genevieve adventures: would not mind seeing these. Nick Briggs himself hams it up as the villian magnificently, and in a clever piece of misdirection the aliens found underneath the Antarctic aren't necessarily who you think will be.