If the nominal transformer primary voltages are the same as the mains supply voltage then the primaries should be connected in parallel. The connection polarities (either primary or secondary) need to be arranged such that the secondary voltages add rather than subtract. By measuring the total secondary voltage you'll soon discover whether the connection polarities are correct or not.
Connect the primaries in parallel...but...the phasing of the primaries must be the same. Connected one way, the series secondaries will add and you get 52Vrms out. Reverse the primary connections and the secondaries subtract, giving you 4Vrms out.