  The Shapley Supercluster ($\langle z \rangle\approx0.048$) contains several
tens of gravitationally bound clusters and groups, making it it is an ideal
subject for radio studies of cluster mergers. We used new high sensitivity
radio observations to investigate the less energetic events of mass assembly in
the Shapley Supercluster from supercluster down to galactic scales. We created
total intensity images of the full region between A 3558 and A 3562, from $\sim
230$ to $\sim 1650$ MHz, using ASKAP, MeerKAT and the GMRT, with sensitivities
ranging from $\sim 6$ to $\sim 100$ $\mu$Jy beam$^{-1}$. We performed a
detailed morphological and spectral study of the extended emission features,
complemented with ESO-VST optical imaging and X-ray data from XMM-Newton. We
report the first GHz frequency detection of extremely low brightness
intercluster diffuse emission on a $\sim 1$ Mpc scale connecting a cluster and
a group, namely: A 3562 and the group SC 1329--313. It is morphologically
similar to the X-ray emission in the region. We also found (1) a radio tail
generated by ram pressure stripping in the galaxy SOS 61086 in SC 1329-313; (2)
a head-tail radio galaxy, whose tail is broken and culminates in a misaligned
bar; (3) ultrasteep diffuse emission at the centre of A 3558. Finally (4), we
confirm the ultra-steep spectrum nature of the radio halo in A 3562. Our study
strongly supports the scenario of a flyby of SC 1329-313 north of A 3562 into
the supercluster core. [abridged...]
