Here are the 6 mistakes I found in the dialogue with corrections:
1. "I afraid we're..." -> I'm afraid we're
2. "...but it's not possible, sir." -> but it's not possible.
3. "Could you to fasten..." -> Could you fasten
4. "...Er, I wonder if I can go..." -> Er, I was wondering if I could go
5. "...But can you being quick..." -> But can you be quick
6. "...please?" -> Please