Bra issue with sleeveless dresses

[MissMillament]

I'm looking for help with the perennial problem of big boobs and sleeveless dresses. Being 36GG I need supportive bras, but they tend to come up so high on the sides that they show through the armholes of sleeveless tops and dresses. Has anyone else with this problem found a style of bra that will provide the requisite support without showing? Or any other creative solutions to this problem? I tend to resort to wearing a cardigan or a vest top underneath, but would like not to have to.
Not sure why manufacturers can't cut the armholes higher in the first place tbh.

I blame the armhole designers and just accept that sometimes my bra will show.

Ewa michalak bras are cut much lower than ones such as panache
Bravissimo own brands sometimes come lower too

The lowest I have found are Comexim, then Ewa Michalak. But I have a large range of colour of bras so if it's a bit of an armpit flasher I match the bra to the the top/dress