You say that the extra charge is because I have provided the legally required documents later than the legal deadline, but still, why is this extra charge?
The extra charge may be two-folded. Firstly, the charge may include any additional charges that the authorities may be applying for the delay in submitting the documents. This is absolutely normal and is very often the case.
Then, there may be an extra cost on our part that needs to be covered. Rather than being able to close your case in the legally foreseen deadline, we have to maintain resources for longer in order to provide the required services. Maintaining these resources is often much more costly to us than the extra charge you may have been charged. Please note that our fees are based on the assumption that the documents that are your responsibility will be provided in a timely manner.