Note: nearly all is said in the comments following your question (and at first by StephenJaifséphaneGimenez).

First, all the proposed variations (including in comments) are correct.

"Si ce n’est pas passer un sale quart d’heure, alors qu’est-ce que c’est ?"

As you’ve removed "colloquial" from the question, the construction "Si ce n’est pas …, alors qu’est-ce que c’est ?" is not colloquial. But "passer un sale quart d’heure" is.

Note that you can also shorten removing "alors": "Si ce n’est pas …, qu’est-ce que c’est ?". This can be considered as a lighter way to say it.

More familiar ways, now, as "si" has no complement, and the following sentences are usually orally used:

"Si ce n’est pas ce qu’on appelle passer un sale quart d’heure !"

"Si ce n’est pas ce qu’on appelle passer un sale quart d’heure, ça !"

"Si ce n’est pas passer un sale quart d’heure !"

"Si ce n’est pas passer un sale quart d’heure, ça !"

About "ça":

It can be placed "anywhere"… the point is to highlight (accentuate) it when you speak. That can also be:

"Ca, si ce n’est pas… !"

"Si ça, ce n’est pas… !"

For more emphasis, you can use "alors" in another way (still orally):

"Alors ça, si ce n’est pas… !"

*"Alors, si ça… !"

Other aspects:

The first sentence "Si xxx, alors xxx ?" is a rhetorical question. So, I’m wondering if the various declinations of it need to keep the interrogation point… To tell the truth, I don’t know. But I think that orally speaking you can tone it as a question.

Additionally, you can invert the locution. For instance (if X then what is not X?):

"si ça c’est un bon match, alors qu’est-ce qu’un mauvais match ?"