How do I report trolls that didn't troll in one of my games?

So I encountered a 3-man jungle premade in flex that banned my hover and my two most played champs, then pasted a whole paragraph in basque into the pre game lobby. Weird and kind of hostile, but it's super low elo, those things happen.

The three of them all picked smite and jungled happily, we didn't have a support or a toplaner but it's fine, it's super low elo, those things happen.

Flex is veeery coinflippy with skill levels and we got lucky, so the adc had hard won her 1v2 lane and I did pretty well in mid, while our jungle trio kept us save from all the jungle creeps.

At 20, they tried to surrender. We didn't, they all disconnected, the adc and I got ready for a 2v5 and 10 seconds later the enemy surrendered. Anticlimactic, but yeah..

So, as strange as that game was, it's neither all that unusual nor did something reportable happen. They weren't helping, but no help was needed, none of our turrets were ever in danger and they also weren't inting. But I was curious enough to look the junglers up and take a peek at a few replays, since the target ban felt a bit like too much effort for normal trolling. Also, I'm super bored rn. They are all on a 20+ loss streak(, with that one win now, and another loss 10 minutes ago). They always ban one teammates most played champs, they always use the same multi-jungle 'strategy' with two core players and a rotating third, they all have reasonable but bad K/D/As and cs ( Which is probably also intentional, since they are Gold+ in Solo Q, so an Iron flex game should be 1v9able for each of them). They pick bad fights and once the enemy starts to breach the base, they'll abandon it and go do dragon or scuttle or something while their Nexus dies.

How do I go about reporting that? All the options I found report the game I was in with then, but that seems to be the one game they didn't have a chance to troll in.