I can relate to this. I did some contracting work for a large bank (let's call them client #1) and had to deal with IBM mainframes connecting their OSA-adapters

I can relate to this. I did some contracting work for a large bank (let's call them client #1) and had to deal with IBM mainframes connecting their OSA-adapters to an IP-network. These adapters talk OSPF to the network and we needed some changes. No one from IBM allocated to my customer then (this is essential..) had any clue. I had to arrange via another colleaugue of mine working for another customer (client #2) who also dealt with IBM that an IBM engineer for his client (#2) talked to the IBM engineer for my client (#1) to have this change done. IBM seems to be silo'd as hell and no one from their team (PM's whatever) seem to be in any rush to contact within IBM to help solve an issue. At the time (2016-2018) their IBM Bluemix cloud offering was a joke. Custom made and in no way a match for AWS/Azure. Luckily I persuaded my client to refrain from using Bluemix and go with Azure/AWS instead.