Hello and welcome,
As you got your fixed appliances,and the treatment was not satisfying,
will ask you to put the appliance again for further corrections.
To an extent,the gap can be closed using removable retainers.
Regarding the charges,it depends on your orthodontist.
Maintain good oral hygiene
Avoid mouthbreathing/tongue thrusting habit if you practice any to correct the occlusion.
Please inform your dentist about your feedback as he can correct it at the same time.
Hope everything becomes fine.