The period for the provision of the services starts to run from the date on which it is signed by the  last party.  The contracting authority orders services by sending the contractor an  Order form  or specific contract  by e-mail or  via e-PRIOR .  The contractor must either: (a) send the  Order form  or specific contract back to the contracting authority signed and dated;  or If the contractor repeatedly refuses to sign the order forms or specific contracts or repeatedly fails to  send them back on time, the contractor may be considered in breach of its obligations under this FWC  as set out in Article II.18.1 (c). The maximum amount covering all purchases under this FWC, including all renewals is EUR 2.700.000  (two millions and seven hundred thousand). However, this does not bind the contracting authority to  purchase for the maximum amount.  The maximum prices of the services shall be as listed in Annex II. [Price revision is determined by the formula set out in Article II.20 and using the trend in the  harmonised  indices  of  consumer  prices  (HICP)  MUICP  published  at  http://ec.europa.eu/eurostat/web/hicp/data/database under HICP (2015 = 100) - monthly data  (index) (prc_hicp_midx).] Reimbursement of expenses is not applicable to this FWC. Pre-financing is not applicable to this FWC.  1. The contractor (or leader in the case of a joint tender) may claim an interim payment of the price  referred to in the relevant specific contract in accordance with Article II.21.6, according to the  following: 6  I.6.2 Interim payments  I.6.1 Pre-financing I.6 PAYMENT ARRANGEMENTS  I.5.3 Reimbursement of expenses  I.5.2 Price revision index  I.5.1 Maximum amount of the FWC and maximum prices I.5 PRICES  I.4.3 Implementation of single FWC  (b) send an explanation of why it cannot accept the order. 