Evidence offered to prove past medical expenses shall be limited to evidence of the amounts actually paid to satisfy the bills that have been satisfied, regardless of the source of payment, and evidence of the amounts actually necessary to satisfy the bills that have been incurred but not yet satisfied. Evidence of the amounts actually necessary to satisfy the bills that have been incurred shall not exceed the amount by which the bills could be satisfied by the claimant’s health insurance, regardless of whether such health insurance is used or will be used to satisfy the bills. This section does not impose upon any party an affirmative duty to seek a reduction in billed charges to which the party is not contractually entitled.