The incorrect employee number message and the fact that the employee is showing as company 0 indicate that there is a discrepancy with the employee details between the information held in Coins payroll and the information held by HMRC.
There are few possibilities of what can be causing the issue
Name is a diminutive. Does it agree with a passport
DOB - typo
NI - Can it be verified with an official document - most common error
EE ID - Have they transferred, can that be seen on the RTI report?
One way to confirm what information is held by HMRC is to download the HMRC desktop viewer:
This will show you the name and NI number of the employee so that these can be eliminated.
If these details are correct, the next step would be to contact HMRC directly to verify the information being held by them.
Once the erroneous data has been found and corrected the tax code change will be applied automatically the next time a notification comes through