Mick, that spring shop fed you a line.

They effed them springs up for you when they re-arched them.

"Spring steel" is beyond my understanding of Metalurgy, but it's a special metal treatment and tampering with it either by cold bending or hot bending ruins them.

Cheapest solution is to get a couple of off-shelf leafs with more arch than what you have now and add them to your spring pack. Hope for the best that your car will sit level on both sides and you get the height you want.