Technical support

If the sensor is defective then you would need to take it to Apple for inspection and an estimate.

Support cannot simply re enable Touch ID if it's been deactivated due to security settings of the device.

How did it get deactivated? If a 3rd party repairer broke it then Touch ID can not be reactivated for any price, because only Apple can do it, and the won't work on phones that have been tampered with.

If it just stopped working on its own here is Apple's service pricing-->iPhone Repair - Official Apple Support