Complex sentence: On 3 May 2013, Coventry City put a contingency plan in place to play elsewhere for the 2013--14 season due to ACL (Arena Coventry Limited), who manage the stadium, not being willing to negotiate with the club to agree a new lease.
Split into simpler sentences: On 3 May 2013, Coventry City put a contingency plan in place to play elsewhere for the 2013--14 season. It was argued by the club that this was due to ACL (Arena Coventry Limited), who manage the stadium, being unwilling to negotiate with the club to agree a new lease.