Denso 13,
Like the earlier poster, I think your Ryanair e-mail is standard for "normal" disruptions; I think the volcanic ash disruptions should be treated separately.
I do think, however, that Ryanair may try to argue that, since you accepted a flight refund, you waived your rights to related compensations. I would certainly dispute this with them. As you imply, they should be liable, at least, for expenses incurred between the cancellation of your first return flight and the last cancelled return flight.
I am sure that there will be many "first refusals" by Ryanair in an attempt to put off claimants but I think it is advisable to continue to pursue them.
On a personal level, I have received no communication in response to my letter and fax. Are you able to publish the e-mail address of the compensation department since it is not available on their website?
Thanks, in advance.