I've figure out my problem...an assumption on my part that there was consistency in the example code I was using. I thought since "i" filled the segments in the characters at the first stage, "i" was also looping through the segments in the second stage (the "Wire.write" procedure.) I now realise the buffer elements hold whole characters, not segments of one character as I thought.
That said, haven't tried it yet, but with help from my best pal (real life coder and programmer) I'm confident it will work...will post back here when it does.
sterretje; yes I posted snippets...but the whole code is present in this thread. I think if I posted the whole sketch each time, there's bound to be someone on here who'd complain that I don't need to repeat myself.