Your instructions were no doubt to obtain a Consent Order. Your solicitor spotted errors which were corrected and for which she charged.
Now, if your solicitor spotted the errors she could have advised you of this (which would have added cost) and sought your instructions. What would your instructions have been?
Would you have instructed your solicitor to write to the other side (at a cost to you) asking them to correct their errors and your solicitor check the amendments upon receipt then submit to the court?
When you appoint a solicitor they stand in your shoes so they act in your best interests. On this occasion she saw the error, corrected it and moved along without incurring the expense of contacting you or contacting the other side (other than to say the error had been corrected) - that is the shortest and most cost-effective route to getting the job done. This is in your best interests.
As for who pays for the error - that is not your ex. The error was your ex's/ex's solicitor's fault and your solicitor caught and corrected it. The court has made no order for costs and you are not going to get one on the back of this issue.
So, in essence, there was a fault, you paid to correct it but it could have a whole lot more expensive had your solicitor raised it as an issue with you.