to be honest, I think the person who has been technically 'wronged' here is your ex as it is he who has the direct relationship with the money, the employer and the CSA! I guess there is no harm in asking but I wouldn't expect anything to come of it.
Your ex, however, if you are on good terms, should be looking at his position from a legal point of view. I have heard of at least one case where the CSA received no money for years, with no contact between PWC and NRP there was no way of either side knowing that the employer should have been paying, but wasn't. When the company went bankrupt, the issue came to light as the CSA sent the NRP a huge billl for money he thought he had paid. The debt remains the NRP's because the money hasn't been paid, even though he has evidence (payslips) that he never received that money in the first place. It is not acceptable that a company behaves in this way - although of course they can argue it was a genuine mistake.
And of course, there is the argument that you can't rely on child maintenance money as part of your income given that you have no control over it or your ex!