As sympathetic as I am as to the reason why you had to travel on this occasion, and accepting that a delay to the first part of your travel plans caused you financial loss, I am not really sure what anybody can say, that hasn't already been said (many times) to provide the confirmation bias you seem to be seeking.
If I recall correctly, your Ryanair flight was delayed 1:45 minutes because of a Generator fault? A delay of that magnitude wouldn't trigger EU 261 compensation as the period is insufficient. Under the contract of carriage there doesn't appear to be anything you can rely on to invoke a remunerated cancellation payment or a delay claim.
The connection times you have quoted (from a commercial guidebook) are recommended minimum connection times that are normally used when a transfer is being ticketed through on the same contract. Beyond that, it is nothing more than a rough guide that you can use as you wish. Given that your first flight was delayed 105 minutes, the connection times (even if they had validity to your claim) would be academic as the reality was it only left you 15 minutes for an International / Domestic non-interline connection.
You booked two different contracts of carriage (on two different airlines, although it wouldn't have made any difference,) and the delay to the first wasn't sufficient to trigger a compensation payment. Consequently, you didn't present in time and as a result forfeited the second contract. Unfortunate, but "you knew the rules."
You (not unreasonably) asked Ryanair to show goodwill towards to you as their delayed flight had caused you a lost opportunity, (saving money by risking two separate contracts that you hoped would work to your benefit in the circumstances). They said "no" and as a result you had to pay circa £140 for a new ticket? The fare you paid was the "standard fare." For it to have been "four times more than usual" you would probably have had to book it at least 4 days in advance, and subject to the yield management offers on that particular flight.
The harsh reality here is that you were hoping two separate tickets with a short transit period between the two, would (fingers crossed) work out to your benefit. It was a gamble and you lost. There are (as you know) options that are much less of a gamble and you elected not to avail yourself of them.
When you asked for a favour from the airline in selling you a new onward ticket at a reduced rate (beyond the terms of the contract) they declined your request. The end result being that you were £140 out of pocket. In all honesty not a great deal in the circumstances.
C'est la vie, but you must realize you are flogging a dead horse? Nevertheless, it is your dead horse to flog and you can keep sending them letters. Trouble is, I cannot see what anybody here can do to help you other than to highlight the pitfalls of buying the right ticket and making sufficient allowance when time is imperative. Caveat emptor!