Conditional Statements in youcanbook.me notifications body for more than one variable to test

Youcanbook.me allows you to use conditional statements within the body of their notifications.

The basic format is:

{IF}{xxx}{EQUALS}yyy{THEN}aaa{ENDIF}

Their doc mentions that they don't support logic operators AND/OR

So the following is not possible:

{IF}{xxx}{EQUALS}yyy{AND}{zzz}{EQUALS}aaa{THEN}bbb{ENDIF}

and they don't seem to support nested IF statements neither. You can't do this:

{IF}{xxx}{EQUALS}yyy{THEN}
    {IF}{zzz}{EQUALS}aaa{THEN}
        bbb
    {ENDIF}
{ENDIF}

¿How, then, can you test for more that one variable? How to solve when you need to print something, say a link, based on a combination of 2 or more variables?