Lancet and Discovery Health putting the patient/member last

My wife had a bone marrow biopsy done by Lancet under a hospital authorisation from Discovery Health. Lancet is a DSP to Discovery, and bound by a payment arrangement, which requires that Lancet bills at Discovery's rates. Discovery didn't pay for the Aspirate Needle, with the reason "This is a non-chargeable item", and short-paid on the Biopsy Needle, with the reason that the it was charged at a rate higher than Discovery's. Between Discovery and Lancet I have been put in the middle of a dispute between them. Discovery advises me I don't have to pay, and Lancet keeps on hounding me for the short-fall. Tumani and Wahfieka at Discovery have both escalated this to their Healthpartners division, and have both promised me feedback, which has not been forthcoming. I logged this query on 27/11/18, and have followed up on 03/12/18 and again today 13/12/18.