Resistance was futile
A colleague and I once spent a good week or so changing the network IP address ranges of 30 regional offices to match the 'harmonised' scheme of the company who'd acquired us. The change was not a major shift in numbering and we were clever enough to do a fair bit of it remotely through deft use of RDP and multihoming. After we'd finished and handed everything over to our new lords and masters (who very soon kicked us regional IT guys out), it transpired they'd forgot to tell us that the subnet masks also needed changing, so off we went again!
This same company ripped out the 8Mbit ADSL VPN connections (this was around 2004) between our HQ and the offices and replaced them with 1/2 Meg MPLS circuits - then wondered why everything ground to a halt (I bet the accountants loved the new bills too!)
The icing on the cake, was that the encumbent IT guys were sh*t scared of Linux and so out went the 300-user email system based on Postfix, to be replaced by MS Exchange + required Licences, and they abandoned the distributed, replicated, cross-site backup system based on BackupPC which performed full and incremental backups of data overnight from every office to two other locations, plus the clever rsync scripts that brought a copy of all regional data back to HQ every night for data mining - we had data coming in from MS-SQL, MS-Access and proprietary systems to be munged into one data set in MySQL - it was bloody brilliant, even if I do say so myself.