Either you are being far too polite re: the sheer bureaucratic incompetence of your former employer - really, a percentage quota? Are people really that stupid? - or something else is wrong - not necessarily with you, of course - and they used your degree as a convenient excuse. Because it's not smart to fire a stats major who can evidently program just because they never majored in CS.

Keep looking.

Now, knowing a few bits of CS might be handy, or fun. But you can self-study. If that's not good enough for an employer, find a better employer.