**It sounds like your minyan follows a misapplication of the opinion of the *Rif*.** 

There are 3 opinions cited in Shulchan Aruch regarding reciting a *bracha* over "Half Hallel". The disagreement is only about the bracha -- All agree to recite Half Hallel. ("Half-Hallel" is said on Rosh Chodesh and Pesach starting Chol Hamoed.)
Also, the only disagreement is abut Half Hallel; Whole Hallel all agree to recite *with a bracha* even with no minyan.

1. The *Rif* (Rabenu Yitzchak Alfasi): a bracha is recited only with a minyan. With no minyan Half Hallel is recited albeit without a bracha

2. Rashi and Rambam (which is followed by Mechaber and Sephardim): not to say bracha *even* with a minyan for Half Hallel

3. The *Tur* (followed by Rema and Ashkenazim, in general): to say Half Hallel with a bracha even with no minyan.

The Rema concludes that to satisfy the opinion of Rif, one should be careful to recite Half Hallel with a minyan.

"Whole Hallel" is said *with a bracha* under all circumstances. Half Hallel is always said *even with no minyan* according to all opinions. The disagreement is only about the bracha over Half Hallel.

Source: Shulchan Aruch 422,2 with Be'er Hagola and Mishne Berurah