No it cannot, Chris.
There are two reasons why this may be so:
1. Many offences for which fines are imposed can only be dealt with by way of a fine (for example many motoring offences). An alternative sentence for the offence itself is therefore not available.
2. Even if the original offence does carry harsher penalties, strange as it may seem, unlike a community order or a suspended sentence order an order to pay a fine cannot be "breached" in the same way and an alternative sentence imposed. To further complicate matters the defaulter may have arrears of fines which were imposed for a number of different offences making resentencing somewhat tricky (e.g. they may have paid some instalments making it messy to determine which fines they have paid and which they have not. They may argue "I've paid the fines imposed for the offences which can carry a community order or custody. It's only the fines for the less serious offences which are outstanding").
The only alternative is to bring the defaulter to the fines enforcement court, examine their means and go through the decision making process we have already discussed, with custody being the only ultimate sanction.