Has it moved from its original position, is it broken or a hazard? I think because of the new guideline you would have to call it a foreign body. If it is just loose but still in deep in the bone and not broken, totally floating out of its original position or a hazard it's 20680 in my opinion. It can go either way I think. If it is still buried in bone I would call it 20680 because the 2819_ area seems more for deep tissue, not bone.
NCCI guidelines state one unit of service for 20680 or 20670 per anatomic site.
"3. The code descriptors for CPT codes 20670 (Removal of implant; superficial...) and 20680 (Removal of implant; deep...) do not define the unit of service. The Centers for Medicare & Medicaid Services (CMS) allows one unit of service for all implants removed from an anatomic site. This single unit of service includes the removal of all screws, rods, plates, wires, etc., from an anatomic site whether through one or more surgical incisions. An additional unit of service may be reported only if implant(s) are removed from a distinct and separate anatomic site."
The payer is probably denying if you are trying to report more than one unit on the same foot even if you use the T mods if they are in the same anatomic area.
Regarding the modifier for 20680 - if it's a toe (phalanx) you could report the T mods, if not phalanx you could do RT or LT to help explain, some payers may not want Ts and want RT/LT, some may not want any mod. I have done 20680 with and without modifiers and have seen it go through either way depending on payer.
Regarding a modifier for 28192 - the MUE is 2 so you're probably not going to get paid for more than one per foot on the same date.