Contract number:  Service contract conditions of December 2018 II.4.4 All periods specified in the contract are calculated in calendar days, unless otherwise  specified. II.4.5  The contractor must not present itself as a representative of the contracting authority  and must inform third parties that it is not part of the European public service.  II.4.6  The contractor is responsible for the  personnel who carry out the services and  exercises its authority over its  personnel without interference by the contracting  authority. The contractor must inform its  personnel  that:  (a) they may not accept any direct instructions from the contracting authority; and  (b) their participation in providing the services does not result in any employment or  contractual relationship with the contracting authority.  II.4.7  The contractor must ensure that the  personnel performing the contract and any future  replacement  personnel  possess the professional qualifications and experience required  to provide the services, as the case may be on the basis of the selection criteria set out  in the tender specifications.  II.4.8 At the contracting authority’s reasoned request, the contractor must replace any  member of  personnel  who:  (a) does not have the expertise required to provide the services; or  (b) has caused disruption at the premises of the contracting authority.  II.4.9 The contractor must record and report to the contracting authority any problem that  affects its ability to provide the services. The report must describe the problem, state  when it started and what action the contractor is taking to resolve it. II.4.10  The contractor must immediately inform the Contracting authority of any changes in  the exclusion situations as declared, according to Article 137 (1) of Regulation (EU)  2018/1046. (a) be made in writing in paper or electronic format in the language of the contract; (b) bear the contract number;  (c) be made using the relevant communication details set out in Article I.8; and  (d) be sent by mail, email or, for the documents specified in the special conditions, via  e- PRIOR . The contractor bears the cost of replacing its  personnel and is responsible for any  delay in providing the services resulting from the replacement of  personnel .  Any communication of information, notices or documents under the contract must:  If a party requests written confirmation of an e-mail within a reasonable time, the other party  must provide an original signed paper version of the communication as soon as possible.  II.5. COMMUNICATION BETWEEN THE PARTIES  II.5.1 Form and means of communication  17 