Subpoena to attend as a witness

I received a subpoena to attend a case as a witness for the Crown. I live 4 hours away from where the trial is taking place. I reached out to the investigating officer 3 weeks ago to inquiry if I can attend virtually. They were to attempt to coordinate this request. As of today, I have no response, court date is set for Monday. I will have to drive to and from the city, stay overnight, miss a day of work and have incidental expenses. What can I claim, if anything? My involvement in this case was simply calling 911. Happy to help, but a virtually option would be ideal for many reasons.